Clamp



June 12, 1928. 1,672,937

J. H. HELMS CLAMP Filed July 1927 when A TTORNEY.

Patented June 12, 1928.

UNITED STA JOHN n. HELMS, or ronrvItLn, morass.

c m-y Application filed July 9,

i This invention relates to clamping devices and pertains particularly to apistonclamp designed primarily for use in connection with pistons or valves of a railway air brake.

The primary object of this invention is to provide, in a manner as hereinafter set forth, an improved type of clamp, designed to be inserted in a portionof the piston for the purpose of securely maintaining. a number of readily separable parts in assembled relation so that the same may beremoved from the piston cylinder as a unit.

Another object of the inventionis to provide, in a manner as hereinafter set forth,

a clampingy device which' oanrbe readily operated to grip the inner walls of a cylinder to secure a firm hold upon the same so that the element may be removedifrom its cylinder housing. i v.

Numerous other objects and advantages of the present invention will become apparent as the description of thesame proceeds and the invention will be best understood from a consideration of the following detailed description taken in connection with the accompanying drawing forming a art of this specification, with the understan mg,"

however, that the invention is not confined to any strict conformit with the showing of the drawing but may he changed or modified so long as such changes or modifications mark no material departure from the salient features of the invention as expressed in the appended claims. 1

In the drawings:

Figure 1 shows a usual form of piston such as is used in railway air brakes showing the same in longitudinal section and showing the device embodying the present inventio applied thereto,

Figure 2 shows the device embodying this invention, removed from engagement with the work,

Figure 3 is a transverse section taken upon the line 3-3 of Figure 1, and

Figure 4 is a section taken transversely of Figure 1 upon the line 44.

Referring now to the drawing in detail wherein like numerals of reference indicate corresponding parts throughout the several views, the numeral 1 indicates the usual type of piston having formed integral therewith the relatively long hollow sleeve 2 over which is slidably fitted a compression spring 3 which is held inposition thereon by the head plate 4, the head plate being provided 1927. Serial No. 204,576.

with central apertures to receive the outer end of thecylinder 2. This outer end of the a cylinder: 1s open as ure 1.

Considerable diflicult is encountered. in removing pistons of t is character from their cylinders as the head plate 4 slides over the sleeve 2 and can be readily forced therefrom under the pressure of the spring 3 thus permitting the parts. to readily separate. r

In order to overcome this objectionable feature; and to hold a piston, spring and head in assembled position,} when removed from the cylinder'inwhich thepiston operates a clamping member is provided consistingof a relatively long shaft indicated as a Whole by the numeral 5 which shaft comprises aishort outer portion 6 and a relatively: long portion 7 provided throughout itslength with screw threads. This portion 7 is of materially lessdiameter than the portionfi and is clearly shown in Figextends throughian aperture 8 formed centrally through a circular plate 9 whichplate iszprovided with the peripheral flange -10.

The plate 9 abuts the shoulder 10 formed at the point of union between the sections 6 and 7 and is thuslimited in its movement upon the threaded shaft 7. The outer end of the shaft section 6 is provided with the hand wheel 11, the utility of which will become apparent as the description proceeds.

The inner face of the head 9 at diametrically opposite points on either side of the opening 8 is provided with the ears 12 and from each of these. ears a relatively long arm 13 extends, the free inner end of which arms terminate in the jaws 14, the outer surface of which are convexed and provided with transverse ridges or teeth 15. As is clearly shown in Figure 4 these jaws 14 are materially broader than the arms 13 and the outer faces thereof are of a curvature to conform to the curvature of the cylinder 2.

The free ends of the arms 13 beneath the jaws 14 are rounded as at 16 and slidably enga e in the tapered groove 17 formed longitu inally of the surface of the nut member 18, which nut is provided with a central longitudinally extended bore 19 which is provided with threads for the reception of the threaded shaft 7 which is designed to extend therethrough as is shown in Figure 1. i

The arms 13 inwardly of the jaw ends each has the transversely extending pin 20 passed therethrough and projecting from the opposite faces thereof and each end of the pin of one arm is connected with the adjacent end of the pin of the other arm by the spring 21. These springs located on opposite sides of the screw 7, act to draw the arms 13 together thus causing the same to grip the nut 18 tightly between their outer ends.

In operation, the arms 13 of the device are extended into the free open end of the cylinder 2 until the plate 9 engages the free end of the cylinder and the flange 10 surrounds the same. The wheel 11 is then rotated inthe proper direction to cause the nut 18 to be drawn toward the wheel upon the threaded shaft or screw 7 thereby forcing apart the free ends of the arms 13 to cause the serrated faces of the jaws 14 to "engage the inner surface of the wall of the cylinder. It will be readily understood that by thisoperation the spread jaws can be caused to tightly grip the cylinderand the flange 10 of the head plate 9 will then prevent the plate 4 from being forced off of the cylinder 2 by the spring 3 and the three elements can be removed as a unit from the piston cylinder.

What I claim is: I a

1. A clamp' of the character described, comprising a threaded shaft, a plate traversed by said shaft and rotatable thereabout, a nut member threaded upon and gitudinally of said shaft and 7 having the movable longitudinally of said shaft and having lon itudinall extending grooves formed in t e face thereof, and a pair of jaw carrying arms normally having pivotal connection at one end with said plate the other end of each arm being slidable in a groove of said 'nut member.

2. A cylinder engaging clamp of the character described, comprising a relatively long shaft having screw threads formed throughout substantially half the length thereof, a plate member traversed by and rotatable about said shaft and having a flange formed about the edge thereof for engagement over the end of a cylinder, a pair of arms arranged longitudinally of the threaded portion of said shaft, means for pivotally securing said arms at one end to said plate, a nut member threaded upon said s aft engaging the free end thereof and eripheral surface provided with a pair 0 tapered grooves, designed to receive the free ends of said arms, jaw members formed upon the free ends of said arms for engagement with. the inner face of a cylinder, and resilient members connecting said arms and normally tending to draw the same together, substantially as and for the purpose described.

In testimony whereof I aflix my signature.

JOHN H. HELMs.

arranged lon- 

